The field of art to which this invention is directed is epoxy-amine adducts useful as curing agents for epoxy resins.
Epoxy-amine adducts, i.e., the reaction products of amines with mono or polyepoxides, have been used as curing agents for epoxy resins for a great number of years. Such adducts have lower volatility than unadducted amines due to their higher molecular weight and therefore cause less environmental problems. By varying the amine and/or the epoxy moiety, curing agents can be made which provide a wide range of properties to cured epoxy resin systems.
In U.S. Pat. No. 2,643,239, epoxy-amine adducts of diepoxides and secondary amines are described.
Epoxy-amine adducts of polyamines and polyepoxides are described in U.S. Pat. Nos. 2,651,589 and 2,909,448.
Various types of epoxy-amine adducts are disclosed in U.S. Pat. Nos. 4,182,831; 4,182,833; 4,525,542; 4,539,347; and 4,608,405.
In recent years due to environmental concerns and governmental regulations, there have been increased efforts made to develop curable epoxy resin systems which contain a minimum of volatile organic compounds and which can be reduced with water.
Many of the known epoxy-amine adducts can be dissolved in water in combination with a water miscible co-solvent. However, they generally cannot be dissolved in water with no organic solvent being present unless they are salted with an acid. The use of organic cosolvents introduces volatile organic compounds into the system. The use of acids for salting reduces the resistance properties of the cured compositions.
There is a need for an epoxy-amine adduct which can be dissolved in water with a minimum of organic cosolvent and which does not need to be salted in order to be soluble in water.